/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.commons.utils;

import java.io.DataOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class BasicStructureSerDeUtil {
    public static final int INT_LEN = 4;

    private BasicStructureSerDeUtil() {
    }

    /**
     * read string from byteBuffer.
     */
    public static String readString(ByteBuffer buffer) {
        int strLength = readInt(buffer);
        if (strLength < 0) {
            return null;
        } else if (strLength == 0) {
            return "";
        }
        byte[] bytes = new byte[strLength];
        buffer.get(bytes, 0, strLength);
        return new String(bytes, 0, strLength);
    }

    /**
     * read string list from byteBuffer.
     */
    public static List<String> readStringList(ByteBuffer buffer) {
        int size = readInt(buffer);
        if (size < 0) {
            return null;
        }
        List<String> stringList = new ArrayList<>();
        for (int i = 0; i < size; i++) {
            stringList.add(readString(buffer));
        }
        return stringList;
    }

    /**
     * read a int var from byteBuffer.
     */
    public static int readInt(ByteBuffer buffer) {
        return buffer.getInt();
    }

    /**
     * write string to byteBuffer.
     *
     * @return the length of string represented by byte[].
     */
    public static int write(String s, ByteBuffer buffer) {
        if (s == null) {
            return write(-1, buffer);
        }
        int len = 0;
        byte[] bytes = s.getBytes();
        len += write(bytes.length, buffer);
        buffer.put(bytes);
        len += bytes.length;
        return len;
    }

    /**
     * write string to byteBuffer.
     *
     * @return the length of string represented by byte[].
     */
    public static int write(String s, DataOutputStream stream) throws IOException {
        if (s == null) {
            return write(-1, stream);
        }
        int len = 0;
        byte[] bytes = s.getBytes();
        len += write(bytes.length, stream);
        stream.write(bytes);
        len += bytes.length;
        return len;
    }

    /**
     * write string list to dataOutputStream.
     *
     * @return the length of string represented by byte[].
     */
    public static int write(List<String> stringList, DataOutputStream stream) throws IOException {
        if (stringList == null) {
            throw new IllegalArgumentException("stringList must not be null!");
        }
        int res = 0;
        int size = stringList.size();
        res += write(size, stream);
        for (String s : stringList) {
            res += write(s, stream);
        }
        return res;
    }

    /**
     * write a int n to byteBuffer.
     *
     * @return The number of bytes used to represent n.
     */
    public static int write(int n, ByteBuffer buffer) {
        buffer.putInt(n);
        return INT_LEN;
    }

    /**
     * write a int n to dataOutputStream.
     *
     * @return The number of bytes used to represent n.
     */
    public static int write(int n, DataOutputStream stream) throws IOException {
        stream.writeInt(n);
        return INT_LEN;
    }

    /**
     * write a map to buffer
     *
     * @return length
     */
    public static int write(Map<String, String> map, ByteBuffer buffer) {
        if (map == null) {
            return write(-1, buffer);
        }

        int length = 0;
        byte[] bytes;
        buffer.putInt(map.size());
        length += 4;
        for (Map.Entry<String, String> entry : map.entrySet()) {
            bytes = entry.getKey().getBytes();
            buffer.putInt(bytes.length);
            length += 4;
            buffer.put(bytes);
            length += bytes.length;
            bytes = entry.getValue().getBytes();
            buffer.putInt(bytes.length);
            length += 4;
            buffer.put(bytes);
            length += bytes.length;
        }
        return length;
    }

    /**
     * write a map to dataOutputStream
     *
     * @return length
     */
    public static int write(Map<String, String> map, DataOutputStream stream) throws IOException {
        if (map == null) {
            return write(-1, stream);
        }

        int length = 0;
        byte[] bytes;
        stream.writeInt(map.size());
        length += 4;
        for (Map.Entry<String, String> entry : map.entrySet()) {
            bytes = entry.getKey().getBytes();
            stream.writeInt(bytes.length);
            length += 4;
            stream.write(bytes);
            length += bytes.length;
            bytes = entry.getValue().getBytes();
            stream.writeInt(bytes.length);
            length += 4;
            stream.write(bytes);
            length += bytes.length;
        }
        return length;
    }

    /**
     * read map from buffer
     */
    public static Map<String, String> readMap(ByteBuffer buffer) {
        int length = readInt(buffer);
        if (length == -1) {
            return null;
        }
        Map<String, String> map = new HashMap<>(length);
        for (int i = 0; i < length; i++) {
            // key
            String key = readString(buffer);
            // value
            String value = readString(buffer);
            map.put(key, value);
        }
        return map;
    }

    /**
     * write a string map to buffer
     *
     * @return length
     */
    public static int writeStringMapLists(Map<String, List<String>> map, ByteBuffer buffer) {
        if (map == null) {
            return write(-1, buffer);
        }

        int length = 0;
        byte[] bytes;
        buffer.putInt(map.size());
        for (Map.Entry<String, List<String>> entry : map.entrySet()) {
            bytes = entry.getKey().getBytes();
            buffer.putInt(bytes.length);
            buffer.put(bytes);
            buffer.putInt(entry.getValue().size());
            entry
                    .getValue()
                    .forEach(
                            b -> {
                                buffer.putInt(b.length());
                                buffer.put(b.getBytes());
                            });
        }
        return length;
    }

    /**
     * read string map from buffer
     */
    public static Map<String, List<String>> readStringMapLists(ByteBuffer buffer) {
        int length = readInt(buffer);
        if (length == -1) {
            return null;
        }
        Map<String, List<String>> map = new HashMap<>(length);
        for (int i = 0; i < length; i++) {
            // key
            String key = readString(buffer);
            // value
            int listSize = readInt(buffer);
            List<String> valueList = new ArrayList<>();
            for (int j = 0; j < listSize; j++) {
                String value = readString(buffer);
                valueList.add(value);
            }
            map.put(key, valueList);
        }
        return map;
    }

    /**
     * write a string map to buffer
     *
     * @return length
     */
    public static int writeIntMapLists(Map<Integer, List<Integer>> map, ByteBuffer buffer) {
        if (map == null) {
            return write(-1, buffer);
        }

        int length = 0;
        buffer.putInt(map.size());
        for (Map.Entry<Integer, List<Integer>> entry : map.entrySet()) {
            buffer.putInt(entry.getKey());
            buffer.putInt(entry.getValue().size());
            entry.getValue().forEach(buffer::putInt);
        }
        return length;
    }

    /**
     * read string map from buffer
     */
    public static Map<Integer, List<Integer>> readIntMapLists(ByteBuffer buffer) {
        int length = readInt(buffer);
        if (length == -1) {
            return null;
        }
        Map<Integer, List<Integer>> map = new HashMap<>(length);
        for (int i = 0; i < length; i++) {
            // key
            int key = readInt(buffer);
            // value
            int listSize = readInt(buffer);
            List<Integer> valueList = new ArrayList<>();
            for (int j = 0; j < listSize; j++) {
                int value = readInt(buffer);
                valueList.add(value);
            }
            map.put(key, valueList);
        }
        return map;
    }
}
